Which of the following functions occurs in the part of the digestive system indicated by the arrow?Secretion of buffers and digestive enzymesAcid breakdown of swallowed foodsSecretion of bile and buffersAbsorption of water and ions

Answer:

12.5 mL of HCl

Explanation:

The balanced chemical equation for the neutralization reaction is as follows

NaOH + HCl —> NaCl + H2O

Molar ratio of NaOH to HCl is 1:1

For neutralization to happen the number of NaOH moles is equal to the number of HCl moles

Number of NaOH moles reacted - 0.20 mol/L x 0.025 L = 0.005 mol

Therefore number of HCl moles reacted - 0.005 mol

Concentration of HCl is 0.40 mol/L

Concentration = number of moles / volume

Rearranging the equation

Volume = number of moles / concentration

Volume = 0.005 mol / 0.40 mol/L

= 0.0125 L

Volume of HCl added is 12.5 mL

pH = 4.20

pKa = -log(6.30 × 10^-5)

pKa = 4.20  

Moles of Benzoic acid = volume × molarity

                                      = 0.050L × 1.00M

                                      = 0.050moles benzoic acid  

Moles of the salt = 0.050L ×  1.00M

                           = 0.050 moles salt  

Therefore;

0.050mols / 0.1 L = 0.50M  

0.050mols / 0.1 L = 0.50M  

Thus;

pH = 4.20 + log(0.50/0.50)

pH = 4.20

From the calculations, the pH of the solution is 4.20

The pH is defined as the degree of acidity or alkalinity of a solution. We have to find the pH of the buffer using the Henderson–Hasselbalch equation.

Since, Ka = 6.30 × 10^-5

then pKa = -log(6.30 × 10^-5)

pKa = 4.20  

Number of moles of Benzoic acid = volume × molarity

= 0.050L × 1.00M = 0.050moles benzoic acid  

Number of moles of benzoate = 0.050L ×  1.00M = 0.050 moles

Total volume of solution = 50 mL + 50 mL = 100 mL or 0.1 L

Molarity of acid

0.050mols / 0.1 L = 0.50M  

Molarity of conjugate base

0.050mols / 0.1 L = 0.50M  

Hence;

pH = 4.20 + log(0.50/0.50)

pH = 4.20

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C. electrons

An ion is formed when electrons are gained or lost.

A reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. Reversible reactions will reach an equilibrium point where the concentrations of the reactants and products will no longer change.

A reversible reaction is a chemical reaction where the reactants form products that, in turn, react together to give the reactants back. Reversible reactions will reach an equilibrium point where the concentrations of the reactants and products will no longer change

The answer is D. forty calories

To find the symbol for the isotope of 58Co with 33 neutrons, we must account for the atomic number of cobalt (27) and the specified number of neutrons (33). The symbol would typically be Co-58 or ^58Co; however, there seems to be a discrepancy as 58Co should have 31 neutrons, not 33.

The symbol for the isotope of 58Co with 33 neutrons is represented as Co-58 or ^58Co. To determine this, we should know that the atomic number of cobalt (Co) is 27, which means it has 27 protons. The number of neutrons is given as 33. The mass number (A) of an isotope is the sum of its protons (Z) and neutrons (N), which in this case is 27 + 33 = 60. However, there may be a slight confusion because the question mentions the symbol for the isotope of 58Co, which suggests the mass number is 58. If that's the case, and we have 27 protons, then this isotope would actually have 58 - 27 = 31 neutrons, not 33. Since the question specifies 33 neutrons, we need to clarify this before providing the correct symbol.

The following molecules can exhibit hydrogen bonding as a pure liquid is NH3 (amonia), HC3 -- O -- OH (methanol), CH3CO2H (acetic acid)

Hydrogen bonding is directly connected to Nitrogen, Oxygen, and Fluoride and it (N, O, F) represents the hydrogen bonding. Whereas molecule is the smallest particle in a chemical element or compound that has the chemical properties of that element or compound

Identify which of the following molecules can exhibit hydrogen bonding as a pure liquid.

Grade:  9

Subject:  chemistry

Chapter:  hydrogen bonding

Keywords: hydrogen bonding, molecules, amonia, tetrafluoromethane, benzaldehyde

The molecules that exhibit hydrogen bonding are ammonia NH3, acetic acid CH3CO2H and H2C20H

Hydrogen bonding refer to am electrostatic force of attraction that exist between a hydrogen atom which is covalently bonded together to an atom that is more electronegative and another electronegative atom that have a lone pair of electrons. the hydrogen bond is the acceptor.

Therefore, The molecules that exhibit hydrogen bonding are ammonia NH3, acetic acid CH3CO2H and H2C20H.

The question is incomplete bit the options are gotten from another website. here are the options below.

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This is true. this bundle results as a result of electron transition between energy levels of a metal upon impact by a fast moving electron. This bundle moves with the speed of light in a vacuum which is approximately 3.0×10⁸m/s.

The answer would be C, because it is the follower up of oxygen.

acids give away protons (H+), bases accept protons, conjugate bases are what u get when when you take the protons from the acid, and conjugate acids are what u get when you add the protons to the base.

so for (a) the C5H5N is the base, water is the acid, C5H5NH+ is the conj acid, OH- is the conj base

(b) HNO3 is the acid, H2O is the base, hydronium ion is the conj. acid, NO3- is the conj base.

Answer: a) [tex]C_5H_5N(aq.)+H_2O(l)\rightarrow C_5H_5NH^+(aq.)+OH(aq.)[/tex]

bronsted- lowry acid : [tex]H_2O[/tex]

conjugate base : [tex]OH^-[/tex]

bronsted- lowry base : [tex]C_5H_5N[/tex]

conjugate acid : [tex]C_5H_5NH^+[/tex]

b) [tex]HNO_3(aq)+H_2O(l)\rightarrow H_3O^+(aq.)+NO_3^-(aq.)[/tex]

bronsted-lowry acid : [tex]HNO_3[/tex]

conjugate base : [tex]NO_3^-[/tex]

bronsted- lowry base : [tex]H_2O[/tex]

conjugate acid : [tex]H_3O^+[/tex]

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

For the given chemical equation:

a) [tex]C_5H_5N(aq.)+H_2O(l)\rightarrow C_5H_5NH^+(aq.)+OH(aq.)[/tex]

Here, [tex]H_2O[/tex] is loosing a proton, thus it is considered as a brønsted-lowry acid and after losing a proton, it forms [tex]OH^-[/tex] which is a conjugate base.

And, [tex]C_5H_5N[/tex] is gaining a proton, thus it is considered as a brønsted-lowry base and after gaining a proton, it forms [tex]C_5H_5NH^+[/tex] which is a conjugate acid.

b) [tex]HNO_3(aq)+H_2O(l)\rightarrow H_3O^+(aq.)+NO_3^-(aq.)[/tex]

Here, [tex]HNO_3[/tex] is loosing a proton, thus it is considered as a brønsted-lowry acid and after losing a proton, it forms [tex]NO_3^-[/tex] which is a conjugate base.

And, [tex]H_2O[/tex] is gaining a proton, thus it is considered as a brønsted-lowry base and after gaining a proton, it forms [tex]H_3O^+[/tex] which is a conjugate acid.

Answer:

The reactions that have a positive ΔSrxn are the second and the fourth:

Explanation:

ΔSrxn stands for the change in entropy of a reaction.

Since ΔSrxn equals Final entropy - Initial entropy, a positive ΔSrxn (ΔSrxn > 0) means that the entropy increases.

Given the chemical equations for some reactions, you can identify the direction of the change of entropy (increase or decrease) by inspection, using basic definitions and principles.

These are:

With those principles, you get the following results for each of the given systems.

1) 2A(g) + B(g) → C(g)

  Since in the product (right) side there are fewer molecules than in the reactant (left) side, you predict that the entropy decreases, and so the ΔSrxn is negative.

2) A(g) + B(g) → 3C(g)

    Since in the product (right) side there are more molecules than in the reactant (left) side, you predict that the entropy increases, and so the ΔSrxn is positive.

3) 2A(g) + 3B(g) → 4C(g)

    Since in the product (right) side there are fewer molecules than in the reactant (left) side, you predict that the entropy decreases, and so the ΔSrxn is negative.

4) 2A(g) + B(s) → 3C(g)

    Since there are the same number of molecules in both sides, the determining factor of the change of entropy is the physical state of the components.

Since the reactant B (s) is in solid state and the only product is C(g), and it is in gas state, you predict that the entropy increases, and ΔSrxn is positive.

Conclusion: the reactions that have a positive ΔSrxn are the second and the fourth:

Answer: C.   Forming the activated complex requires energy.

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

In order that reactants change into products, they have to cross an energy barrier. When reactant molecules absorb energy, their bonds are loosened and new loose bonds are formed between them.

The intermediate thus formed is called as activation complex. It is unstable and immediately dissociates to form stable products by release of energy.

Answer:

B. Keq = [SO₃][NO]/[SO₂][NO₂].

Explanation:

Keq = [products]/[reactants].

∴ Keq = [SO₃][NO]/[SO₂][NO₂].

The formula unit for the compound formed when each pairs of ions interact are as mentioned below-

Li⁺ and 0²⁻ forms Li2O

Mg²⁺ and S²⁻ forms Mg S

A1³⁺ and CI⁻ forms AlCl3Na⁺ and

N³⁻ forms Na3N

The formula unit is the smallest unit of an ionic substance that tells us  of the ratio in which ions are combined in the ionic compound.

The formula unit for the compounds formed depends on the valency of the combining ions.

Usually, the formula unit is written on the valency of the ions.

The formula unit for the compound formed when each pairs of ions interact are therefore as written-

Li⁺ 0²⁻ forms Li2O

Mg²⁺S²⁻ forms Mg S

A1⁺³  CI⁻ forms AlCl3 and

Na+ N³⁻ forms Na3N.

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Answer:

d) Metallic character decreases as you go to the right across a row in the periodic table and increases as you go down a column.

Explanation:

The term amphoteric describes a substance that can act as both an acid and a base.

The moles of acid (HCOOH) and base (NaOH) were calculated based on their respective volumes and concentrations. The moles of excess acid, along with the total volume, were used to determine the concentration of excess acid. Using this concentration, the pH during the titration was found to be 3.336.

Calculate the moles of acid and base:

Moles of HCOOH = (Volume) * (Concentration) = (30.0 mL) * (0.1000 M)

Moles of NaOH = (29.3 mL) * (0.1000 M)

Calculate the moles of excess acid:

Moles of excess HCOOH = (Moles of HCOOH) - (Moles of NaOH)

Calculate the concentration of excess acid:

Concentration of excess HCOOH = (Moles of excess HCOOH) / (Total volume)

Total volume = 30.0 mL + 29.3 mL

Use the concentration of excess acid to find [H+]:

[H+] = sqrt(Ka * Concentration of excess HCOOH)

The formula [H+] = sqrt(Ka * C) comes from the equilibrium expression for a weak acid, where C is the concentration of the acid.

Calculate pH:

pH = -log[H+]

Now, let's substitute the values:

Moles of HCOOH = (30.0 mL) * (0.1000 M) = 0.003 moles

Moles of NaOH = (29.3 mL) * (0.1000 M) = 0.00293 moles

Moles of excess HCOOH = 0.003 moles - 0.00293 moles = 6.72 x 10^-5 moles

Total volume = 30.0 mL + 29.3 mL = 59.3 mL = 0.0593 L

Concentration of excess HCOOH = (6.72 x 10^-5 moles) / (0.0593 L) = 1.13 x 10^-3 M

[H+] = sqrt((1.8 x 10^-4) * (1.13 x 10^-3 M)) = 4.61 x 10^-4 M

pH = -log(4.61 x 10^-4) = 3.336

Therefore, the pH during the titration is 3.336.

Answer: A.) always near the same molecules

Explanation:

The capillary action of water is the movement of water from roots to the leaves and other plant parts against the gravitational force of earth. This conduction of water is facilitated by the two properties of water that are cohesion and adhesion.

Cohesion can be define as the attraction of the molecule of water towards another water molecule. Adhesion can be define as the attraction of the molecules of water towards the different type of molecule.  

Among the given options A is the correct option because of the fact that the attraction of water molecules among themselves gives water a definite volume in the glass. Cohesive forces keeps the water molecules close together.      

As a water molecule in a glass of water, you are constantly running into different molecules due to the higher kinetic energy in the liquid state which allows free movement, with transient hydrogen bonding creating temporary clusters.

In a liquid state, such as being a water molecule in a glass of water, you would experience a dynamic and ever-changing environment. If we imagine ourselves as a water molecule, we would be in constant motion, with hydrogen bonds forming and breaking as we interact with our neighboring molecules. Unlike in a solid where molecules are in a fixed position and only vibrate, in a liquid state, the molecules have more energy allowing them to move around freely, although they are still close to each other. This movement leads to different clusters or ''clumps'' of molecules circulating within the confines of the container.

The correct answer to the given question is C.) constantly running into different molecules. Water molecules in a liquid phase such as in a glass of water are not held in a rigid pattern, nor are they always near the same molecules because their increased kinetic energy allows them to move and trade places with one another. This movement is random yet constrained by the surface of the liquid. The hydrogen bonding that occurs is transient - while it does create some structure, it is not rigid or permanent.

The velocity of any gas particles is inversely proportional to the molecular mass of the the gases. Lighter gases posses higher kinetic energy than heavier gases. From the list given, Neon is the lightest of the four gases with an atomic mass of 4.03 thus it is the lightest. Velocity contributes to the  Kinetic energy of the particle. Thus A) Neon is the correct answer.

Answer: The correct answer is Option A.

Explanation:

Velocity of the gas is inversely related to the molar mass of the given gas. The equation representing the relation between the two is:

[tex]\text{Velocity of the gas}\propto \frac{1}{\sqrt{\text{Molar mass of the gas}}}[/tex]

From the above relation, if the molar mass of the gas is more, the velocity of the gas will be less and vice-versa.

The molar masses of the given gases are as:

Ne = 20 g/mol

[tex]O_2[/tex] = 32 g/mol

Ar = 40 g/mol

[tex]N_2[/tex] = 28 g/mol

As, the molar mass of neon is the lowest. Thus, it will have the highest velocity.

Hence, the correct answer is Option A.

Answer:

A. mL/s.

Explanation:

Rate of the reaction = Δ[C]/Δt.

If we take the volume (mL) expressing the concentration. So, the unit of the rate of the reaction is (mL/s).

rate = k{A}^2{B}^2

When having a reaction both need to be included, so we know that D wouldn't work for us. But since they are being combined they would both be squared with 2. Then they would form compounds of C and D.

Answer:

There are many possible combinations of atoms

Explanation:

Atoms in the periodic table can combine in a myriad of ways – sometimes quoted to approximately 10^78 combinations.  To understand the enormity, carbon (and its ability to form numbers combination with other elements) is the main element significant in the variations of organic life on earth.

Answer:

There are many possible combinations of atoms

Explanation:

This is based on the Law of Multiple Proportion. Two different elements can combine in different ratio to create multiple compounds. Let’s take the example of CO and CO₂. In carbon monoxide there is 1:1 ratio of C:O and in carbon dioxide the ration of C:O is 1:2. Because of the difference in combination ratios of the individual elements the two compounds have different physical and chemical property.

Answer:

a. 5.10.

b. 4.35.

c. 5.10.

d. 4.35.

Explanation:

a. 0.10 M acetic acid/0.25 M sodium acetate

For acidic buffer:

∵ pH = pKa + log [salt]/[Acid]

∴ pH = - log(Ka) + log [salt]/[Acid]

Ka for acetic acid = 1.8 x 10⁻⁵.

∴ pH = - log(1.8 x 10⁻⁵) + log(0.25)/(0.10)

∴ pH = 4.744 + 0.34 = 5.084 ≅ 5.10.

b. 0.25 M acetic acid/0.10 M sodium acetate

For acidic buffer:

∵ pH = pKa + log [salt]/[Acid]

∴ pH = - log(Ka) + log [salt]/[Acid]

Ka for acetic acid = 1.8 x 10⁻⁵.

∴ pH = - log(1.8 x 10⁻⁵) + log(0.10)/(0.25)

∴ pH = 4.744 - 0.34 = 4.346 ≅ 4.35.

c. 0.080 M acetic acid/0.20 M sodium acetate

For acidic buffer:

∵ pH = pKa + log [salt]/[Acid]

∴ pH = - log(Ka) + log [salt]/[Acid]

Ka for acetic acid = 1.8 x 10⁻⁵.

∴ pH = - log(1.8 x 10⁻⁵) + log(0.20)/(0.08)

∴ pH =  4.744 + 0.34 = 5.084 ≅ 5.10.

d. 0.20 M acetic acid/0.080 M sodium acetate

For acidic buffer:

∵ pH = pKa + log [salt]/[Acid]

∴ pH = - log(Ka) + log [salt]/[Acid]

Ka for acetic acid = 1.8 x 10⁻⁵.

∴ pH = - log(1.8 x 10⁻⁵) + log(0.08)/(0.20)

∴ pH = 4.744 - 0.34 = 4.346 ≅ 4.35.

The pH of various acetic acid and sodium acetate buffered solutions can be calculated using the Henderson-Hasselbalch equation. The pH values are 5.14, 4.34, 5.04, and 4.44 respectively. A good buffer should ideally have equal concentrations of acid and base.

To calculate the pH of each buffered solution, we will use the Henderson-Hasselbalch equation, which is pH = pKa + log([A⁻]/[HA]), where [A⁻] is the molar concentration of the base (sodium acetate) and [HA] is the molar concentration of the acid (acetic acid).

Firstly, we need to know the pKa of acetic acid. The Ka of acetic acid is 1.8 x 10⁻⁵, therefore, the pKa = -log(Ka) = 4.74.

Remember, a good buffer should have about equal concentrations of both of its components for best buffering capacity.

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Answer:

(first choice)

One difference between first- and second-order reactions is that the half-life of a first-order reaction does not depend on [Ao]; the half-life of a second-order reaction does depend on [Ao].

Explanation:

1) First order reactions' model

This is a brief deduction of the first order reactions' half-life

       - d[A]/[A] = kdt ⇒ - ln { [A]/[Ao] } = kt

       t half-life = T

       [A] = (1/2) [Ao] ⇒- ln { [A]/[Ao] } = - ln (1/2) = ln(2) = kT

       ⇒ T = ln(2) / T

        * The half-life of a first order reaction is a constant; it does not depend on the initial concentration of the reactants, it only depend on the rate constant.

2) Second order reaction's model:

This is a brief deduction of the second order reactions' half-life

       - d[A]/[A]² = kdt ⇒ 1/[Ao] - 1/[A] = kt

       t half-life = T

       [A] = (1/2) [Ao] ⇒ 1 / [Ao] - 1 / {2[Ao]} = 1 / {2[Ao]} = kT

       ⇒ T =   1 / {2k[Ao] }

        * The half-life of a second order reaction depends on the initial concentration and the rate constant.

3) Final conclusion:

We have found that while the half life of a first order reaction is does not depend on the initial concentration, the half-life of a second order reaction does depends on the initial concentration. Hence, the correct answer to the question is:

One difference between first- and second-order reactions is that the half-life of a first-order reaction does not depend on [Ao]; the half-life of a second-order reaction does depend on [Ao].      

The key distinction between first- and second-order reactions lies in the impact of initial reactant concentrations on half-life. In first-order reactions, half-life remains constant, irrespective of initial reactant concentration. For second-order reactions, half-life decreases as reactant concentration increases.

One major difference between first- and second-order reactions is found in the relationship between reaction half-life and initial reactant concentration. In a first-order reaction, the half-life is independent of initial reactant concentration, meaning it stays consistent regardless of the amount of reactant present initially. On the other hand, in a second-order reaction, the half-life is dependent on the initial reactant concentration; specifically, the half-life decreases as the concentration increases. The relationship for a second-order reaction follows this formula: t1/2 is inversely proportional to the initial concentration [A]₀. As the reaction proceeds and the reactant concentration decreases, the half-life increases.

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The final temperature of a mixture of two volumes of water at different temperatures can be found using the principle of heat transfer. The heat lost by the hotter water will be equal to the heat gained by the cooler water. The final temperature is computed using the formula for heat, q = mcΔT.

The exercise in question involves the concept of heat transfer, a fundamental concept in Physics. When two bodies of different temperatures are combined, the heat will flow from the hotter to the cooler body until thermal equilibrium is reached, and both bodies have the same temperature.

Using the principle of heat transfer, we consider that the heat lost by the hotter water will be equal to the heat gained by the cooler water. The formula for heat is q = mcΔT where m is mass, c is specific heat, and ΔT is the change in temperature. Using the density of water as 1 g/mL, we calculate the mass of both volumes of water (370.0 g for the cooler water and 110.0 g for the hotter water). The specific heat of water is 4.184 J/g °C. With this, we set up the equation (370.0 g * 4.184 J/g °C * (Tfinal - 25.00 °C)) = (110.0 g * 4.184 J/g °C * (95.00 °C - Tfinal)), and solve for Tfinal, which represents the final temperature of the mixture.

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Sodium Iodide: NaI

Magnesium Iodide: MgI2

Ionic compound are named by giving the name of metals first. The formula of sodium iodide is NaI and the formula of magnesium iodide is MgI₂.

Ionic compounds are formed through  electron lose from a metal to a non-metal. Metals are electron rich and they will easily lose electrons to attain stability. Whereas, non-metals are mostly electron deficient and they gain electron from metals to form ionic bonds.

Sodium loss its one valence electron to iodine which is also having a valency of one. Hence one electron transfer from sodium to iodine make the compound sodium iodide with the formula NaI.

Magnesium is a divalent metal which needs to loss two electrons to attain stability and thus will binds to two other nonmetals each are provided with an electron.  Therefore, the chemical formula of magnesium iodide is MgI₂.

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I am almost positive that the answer is D

Answer : The correct option is, (B) Cellular respiration in humans

Explanation :

Combustion reaction : It is defined as the hydrocarbon react with the oxygen then it react to give carbon dioxide and water as a product.

A. Photosynthesis in plants

Photosynthesis : It is a chemical process or a reaction which takes place in the green plants or the living organisms.

During this process, the carbon dioxide reacts with the water in the presence of sunlight to gives glucose and oxygen as a product.  

The balanced chemical reaction will be,

[tex]6CO_2+6H_2O\overset{sunlight}\rightarrow C_6H_{12}O_6+6O_2[/tex]

B. Cellular respiration in humans

Cellular respiration : In this process, the hydrocarbon react with the oxygen to give carbon dioxide and water as a product. This reaction is a combustion reaction.

Cellular respiration is directly opposite of photosynthesis.

The balanced chemical reaction will be,

[tex]C_6H_{12}O_6+6O_2\rightarrow 6CO_2+6H_2O[/tex]

C. Mixing of vinegar and baking soda

When vinegar is react with baking soda then it gives sodium acetate, carbon dioxide and water as a product. This reaction is an acid-base reaction.

The balanced chemical reaction will be,

[tex]CH_3COOH+NaHCO_3\rightarrow CH_3COONa+H_2O+CO_2[/tex]

D. Release of carbon dioxide on heating limestone

When limestone (calcium carbonate) is heated then it decomposes to give calcium oxide and carbon dioxide as a product. This reaction is a decomposition reaction.

The balanced chemical reaction will be,

[tex]CaCO_3\rightarrow CaO+CO_2[/tex]

Hence, from this we conclude that the example of combustion reaction is, (B) Cellular respiration in humans

According to what I know, if the water is pure, it always freezes at 0°C.

- Lee Hae :) Have a great day!

If 50 mL of boiling water is added to 100 mL of ice water and the entire mixture is put in a freezer, the water will freeze at 0 [tex]^oC[/tex].

Irrespective of the initial temperature, water always freezes when its temperature drops to zero degrees Celsius, 32 degrees Fahrenheit, or 273 Kelvin.

The freezing happens at the quoted temperature under standard atmospheric pressure and if the water is pure. At higher pressure, the freezing point is lower and at lower pressure, the freezing point increases.

Impurities also lower the freezing point of water

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